Implementation of direction-of-arrival estimation using Rotman lens array antenna

This study presents an implementation of direction-of-arrival estimation using signals received from a Rotman lens array antenna. The algorithm is based on the magnitude comparison method. The Rotman lens array provides multiple beams toward different directions simultaneously. The beam port outputs, which are converted to the video band using envelope detectors, form an output vector. It is used to find the most likely arriving angle based on a higher order interpolation process. In this work, a planar Rotman lens consists of 6 antenna ports and 13 beam ports was fabricated with an FR4 printed circuit board. The lens was connected to 6 broadband Vivaldi horns to form the receiving array. Array patterns are verified in a spherical near field chamber, while the direction finding algorithm was implemented offline using data taken from an open site. Improved direction finding accuracy demonstrates the effectiveness of the proposed Rotman lens array antenna and the developed algorithm.